I'm also very interested in having a functional 68K LLVM backend. It seems there hasn't been any more commits in the above github repositories since 2015. How much work do you believe is still to be done? I've never written an LLVM backend, nor know IR either, so I'm not sure if I could do anything about this. Some comments in this thread, about the difficulty of writing an LLVM backend are discouraging to say the least...